Ubadah bin As-Samit narrated:
"Allah's Messenger prayed the Subh prayer, and he had difficulty with the recitation. When turned (after finishing) he said: 'I think that you are reciting behind your Imam?'" He said: "We said: 'Yes, Messenger of Allah, by Allah!' He said: 'Do not do that, except for Umm Al-Kitab, for there is no Salat for one who does not recite it.'"